Reforestation to fight climate change impacts has limits

Tree planting - main
Constraints can make it unlikely for South-East Asia to enjoy full benefits of reforestation and its impact in mitigating the effects of climate change. Copyright: Un Yarat/US Embassy Phnom Penh (CC BY-ND 2.0).

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  • Reforestation not a universal solution against climate change
  • Less than 18 per cent of land in South-East Asia suitable for reforestation
  • However, reforestation remains a powerful mitigation strategy

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[NEW YORK] Reforestation as a method of mitigating climate change has limitations and, in some cases, the costs can be prohibitive, says a new study.  
Koh Lian Pin, an author of the study and director, Centre for Nature-Based Climate Solutions at the National University of Singapore (NUS), says the study, published in Nature Climate Change, is the first to take a “critical look at reforestation as a climate solution in South-East Asia”.

“Although there are 121 million hectares of degraded lands [in South-East Asia] that are potentially suitable for reforestation, only a fraction of that potential may be achievable if practical constraints are taken into account”

Koh Lian Pin, National University of Singapore

Reforestation has long been a strategy against climate change. Since 2011, the Bonn Challenge has been pushing to restore 150 million hectares of degraded forests through reforestation by 2020 and 350 million hectares by 2030.
“We found that although there are 121 million hectares of degraded lands [in South-East Asia] that are potentially suitable for reforestation, only a fraction of that potential may be achievable if practical constraints are taken into account,” says Koh. “These constraints include the costs of reforestation and other competing uses of the land.” 

Forests in South-East Asia
Maps showing the spatially allocated projected forest cover changes in Southeast Asia under the five shared socioeconomic pathways (SSPs) (2015–2050).
Image credit: Nature Communications (CC BY 4.0).

The study researchers found that when a combination of on-the-ground financial, land use and operational constraints are considered, only a fraction of the mitigation potential may be achievable (0.3–18 per cent). They stressed that careful planning and consideration are needed for effective landscape-scale reforestation.
“The barriers to reforestation that we have identified are not insurmountable,” says Koh. “For example, by involving smallholder farmers in the reforestation process, such as through agroforestry or tree planting on their farms, climate mitigation potential can be realised while balancing trade-offs with food security and local livelihoods.”
Zeng Yiwen, postdoctoral research fellow, department of biological sciences, NUS, and one of the study’s authors, says reforestation is a cost-effective nature-based climate solution with huge potential for mitigating greenhouse gas emissions. “However, we also know that many financial, land use and operational considerations can limit this potential.”
Zeng says the research shows how a consideration of trade-offs (e.g. opportunity costs from agriculture) can limit the climate mitigation potential of reforestation. 
“There is a huge potential for nature-based climate solutions, but also many competing interests for the land,” says Zeng. “One of the main aims of the study was to figure out how we can achieve conservation and climate goals and inform climate policies/decisions in ways that are practical, economically feasible and socially acceptable.”
Roman Carrasco, in the department of biological sciences at NUS and another co-author, tells SciDev.Net: “These important constraints to reforestation do not detract from the fact that reforestation remains one of our most powerful strategies to combat climate change. We need a strong commitment from regional governments to ensure reforestation is effective in South-East Asia.”
Reforestation has multiple co-benefits not included in the study, says Carrasco. “For instance, reforestation is critical to conserve our rich yet imperilled biodiversity in South-East Asia. Reforestation can also help to recover critical ecosystem services such as water provision and regulation, pollination and recreation, among others.”

Pablo Pacheco, global forests lead scientist, WWF, believes the research draws attention to financial and operational constraints in reforestation projects, and that such efforts should be inclusive, adapted to context, and incorporate the needs of local farmers. “WWF has long stressed that for tree planting to have tangible benefits, it must be done in consultation with local communities, have broad political support, done in the right place, and be complemented by strategies to protect existing forests and reduce carbon emissions.”
He adds: “Our work on the ground has shown that forest landscape restoration can positively impact people, nature and climate when factoring in the local context and when conducted with active engagement of communities and the public sector.”
Rupesh Bhomia, a scientist with the Center for International Forestry Research says the study is important as “we embark on a UN-promoted Decade on Ecosystem Restoration next year. Such analysis can inform climate policies and help decision-makers prioritise areas most suitable to achieve restoration success”.
This piece was produced by SciDev.Net’s Asia & Pacific desk.